Vettel dominated last year winning the last nine GPs, but the German was not optimistic about his chances in Melbourne after severe problems in testing as Red Bull adapt to a raft of technical changes.

But he said the Austrian team, led by their design guru Adrian Newey, would soon be back in the hunt as the season unfolds.

"For this race probably Mercedes based on winter testing," the German told reporters, when asked who would win the season opener.

"For the season, after three or four races we'll know a little bit more."

"Our testing and preparation hasn't been ideal and we are not in the best position for this race, but there's a long way to go," Vettel added.

"It's obviously a tough step for all the teams and the drivers, there's a lot of new regulations to get used to.

"We know we're not in the best shape yet. There's a lot of things we need to solve, and unfortunately you can't solve them overnight."

Vettel is bidding to emulate compatriot Michael Schumacher's five consecutive world titles for Ferrari from 2000-2004, and would set a new record if he can win his 10th race in a row.

Despite Red Bull's difficulties in integrating a new engine, he is far from putting up the white flag and insisted he would "push to the maximum" in Sunday's race.

"It's difficult to have any sort of expectations for most of us," he said.

"But it's a long season so I'm going out here not trying to just to make it round. I'm going out here to push to the maximum and do the best I can and then we will see where we are.

"The target for sure is to finish and to finish in the best possible position.

"For the rest of the year we are a strong team, we have a lot of good people on board and we have strong resources so I'm confident we should progress as the season goes on."

Mercedes's Lewis Hamilton, the 2008 world champion, is the nominal pre-race favourite and he appeared to be sizing up team-mate Nico Rosberg as his big rival.

"It's very technical this year and everyone is in the same boat and everyone is trying to see where the advantage is going to be between the two drivers," he said, referring to Rosberg.

"From race to race I think you're going to see one time he's ahead, and another time I'm ahead, the same that you saw last year. The goal is to be ahead on the track."

Ferrari is another team feeling its way after inconclusive winter testing but with a super-competitive driving team in former world champions Fernando Alonso and Kimi Raikkonen.

"It's very difficult to tell how competitive we are at the moment and we will know some answers in the next 24-48 hours," said Spanish driver Alonso.

"I think the car itself and the technology that Formula One has brought this year is a little complex for everyone and we are learning and developing the car every day."

The F1 cars take to Melbourne's Albert Park circuit on Friday for the first of two practice sessions ahead of Saturday's qualifying for grid positions for Sunday's race.